From: James Morse james.morse@arm.com

cpu_pm_enter() calls the pm notifier chain with CPU_PM_ENTER, then if there is a failure: CPU_PM_ENTER_FAILED.

When KVM receives CPU_PM_ENTER it calls cpu_hyp_reset() which will return us to the hyp-stub. If we subsequently get a CPU_PM_ENTER_FAILED, KVM does nothing, leaving the CPU running with the hyp-stub, at odds with kvm_arm_hardware_enabled.

Add CPU_PM_ENTER_FAILED as a fallthrough for CPU_PM_EXIT, this reloads KVM based on kvm_arm_hardware_enabled. This is safe even if CPU_PM_ENTER never gets as far as KVM, as cpu_hyp_reinit() calls cpu_hyp_reset() to make sure the hyp-stub is loaded before reloading KVM.

Fixes: 67f691976662 ("arm64: kvm: allows kvm cpu hotplug") Cc: stable@vger.kernel.org # v4.7+ CC: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Reviewed-by: Christoffer Dall christoffer.dall@linaro.org Signed-off-by: James Morse james.morse@arm.com Signed-off-by: Christoffer Dall christoffer.dall@linaro.org --- virt/kvm/arm/arm.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 59d8e04c19fa..639dca0c0560 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -1262,6 +1262,7 @@ static int hyp_init_cpu_pm_notifier(struct notifier_block *self, cpu_hyp_reset();

return NOTIFY_OK; + case CPU_PM_ENTER_FAILED: case CPU_PM_EXIT: if (__this_cpu_read(kvm_arm_hardware_enabled)) /* The hardware was enabled before suspend. */